If a first screening test shows signs of syphilis, another test is done to confirm a syphilis infection.

Screening tests

Tests used to screen for syphilis include:

Venereal disease research laboratory (VDRL) test. The VDRL test checks blood or spinal fluid for an antibody that can be
produced in people who have syphilis. This antibody is not produced as a
reaction to syphilis specifically, so the test result could be "abnormal" for reasons other than syphilis.

Rapid immunochromatographic test. This test checks for antibodies that are specific to syphilis. Unlike other tests, the blood sample is not sent to a laboratory. You can find out the results at your doctor visit.

Tests to confirm syphilis

Tests used to confirm a syphilis infection include:

Enzyme immunoassay (EIA) test. This blood test checks for syphilis antibodies. A positive EIA test should be confirmed with
either the VDRL or RPR tests.

Fluorescent treponemal antibody absorption (FTA-ABS) test. This test also checks for antibodies. It can be used to find syphilis except during
the first 3 to 4 weeks after exposure. The test can be done on a
sample of blood or spinal fluid.

Treponema pallidum particle agglutination assay (TPPA). This test also checks for antibodies. It is used after another method tests positive for syphilis. This test is not done on spinal fluid.

Darkfield microscopy. This test uses a special microscope to
look for the syphilis germ in a sample of fluid or tissue from an open sore. This test is used mainly to diagnose syphilis
in an early stage.

Microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after
another test shows positive results for syphilis.

Why It Is Done

A syphilis infection can spread through the bloodstream to all
parts of the body. If not treated, syphilis can cause severe heart disease,
brain damage, spinal cord damage, blindness, and death.

A test for syphilis is done to:

Screen for syphilis or check how well treatment is working. Screening tests help your doctor look for a certain disease
or condition before any symptoms appear. This increases the chance of finding
the infection when it can be cured or treated to avoid long-term problems.

The Centers for
Disease Control and Prevention (CDC) and the U.S. Preventive Services Task
Force (USPSTF) recommend that all pregnant women be screened
for syphilis early in pregnancy.footnote 1, footnote 2

Confirm that a person has syphilis.

Screening for
syphilis and other sexually transmitted infections is often done for
people who engage in
sexual behaviors that put them at risk. If you have syphilis, your
sex partner or partners should be told, tested, and treated to prevent
serious problems and to stop the spread of the disease.

How To Prepare

Are allergic to any
medicines, especially antibiotics or medicine used to numb the skin
(anesthetics).

Have had bleeding problems or take blood-thinners,
such as aspirin or warfarin (Coumadin).

Are or might be
pregnant.

If you have syphilis, do not have sex until
the test results show that you are no longer infected or until you and your sex
partner or partners have completed treatment and the infection has been cured.
Your sex partners should be tested as well.

If you think you might have syphilis, do not
have sex until testing shows that you are not infected.

Talk to your doctor about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results may mean. To help you understand the importance of this test, fill
out the
medical test information form(What is a PDF document?).

How It Is Done

A syphilis test may be done on a sample of blood, sore, skin, or
spinal fluid, depending on which type of test is done.

Blood sample

Blood test from a finger stick

For a fingertip sample, the health professional taking the sample will:

Clean your hand with soap and warm water or an alcohol swab.

Massage your hand without touching the puncture site.

Puncture the skin on the side of your middle or ring finger with a small instrument called a lancet.

Wipe away the first drop of blood.

Place a small tube on the puncture site and collect a small amount of blood.

Put a gauze pad or cotton ball over the puncture site as the tube is removed.

Put pressure on the site and then put on a bandage.

Blood test from a vein

The health professional taking a sample of your blood
will:

Wrap an elastic band around your upper arm to stop the flow of
blood. This makes the veins below the band larger so it is easier to put a
needle into the vein.

Clean the needle site with alcohol.

Put the
needle into the vein. More than one needle stick may be needed.

Attach a tube to the needle to fill it with blood.

Remove the band
from your arm when enough blood is collected.

Put a gauze pad or
cotton ball over the needle site as the needle is removed.

Put
pressure on the site and then put on a bandage.

Sore or skin sample

A sample of fluid or tissue may be taken from an open sore
or from a rash that might be caused by syphilis.

A fluid sample is obtained by gently pressing
the sore.

Skin or
mucous membrane samples may be obtained by gently
rubbing a cotton-tipped swab over the area.

Spinal fluid sample

A spinal tap (lumbar puncture) is done to collect a
spinal fluid sample for syphilis testing.

For a lumbar puncture, a thin needle is inserted into the spinal
canal in the lower back. After the needle is in place, a small amount of
fluid is removed from the spinal canal. To learn more, see the topic
Lumbar Puncture.

How It Feels

Blood sample

The blood sample is taken from a vein in your arm or from your fingertip. You may feel nothing
at all from the needle or lancet, or you may feel a quick sting or pinch. When blood is taken from a vein, an elastic band is wrapped around your upper arm and may feel tight.

Sore or skin sample

You may feel some discomfort when fluid is collected from an open
sore. But syphilis sores usually are not very tender or painful.

Spinal fluid sample

You may feel some discomfort during a lumbar puncture to collect
spinal fluid. To learn more, see the topic
Lumbar Puncture.

Risks

Blood sample

There is very little chance of a problem from having a blood sample
taken from your fingertip or a vein.

You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
minutes.

In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.

Bleeding can be a
problem for people who have bleeding disorders or who take blood-thinning medicines such as aspirin or warfarin (Coumadin). If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.

Sore or skin sample

There is very little risk of problems from having a sample
taken from an open sore, skin rash, or mucous membrane.

Spinal fluid sample

There is little risk linked with having a lumbar puncture to
obtain a spinal fluid sample. To learn more, see
the topic
Lumbar Puncture.

Results

Syphilis tests tell if a person has the disease. They look for antibodies to the bacterium, or germ, that causes
syphilis. Some tests look for the syphilis germ itself.

Results are usually available in 7 to 10 days.

Darkfield microscopic examination

Normal:

No syphilis germs are seen.

Abnormal:

Syphilis germs are seen.

Syphilis tests of blood and spinal fluid

Normal:

No syphilis antibodies are found. This is called a
nonreactive or negative result.

Abnormal:

Antibodies are found. This is called a
reactive or positive test.

A result that is not clearly normal or abnormal is called
inconclusive or equivocal.

With
treatment, a positive VDRL or RPR test result usually
becomes negative. Positive FTA-ABS, MHA-TP, TPPA, or rapid immunochromatographic tests stay
positive for a lifetime, even after syphilis has been cured.

In the United States, your health professional must report to the
state health department that you have syphilis.

Syphilis and HIV infection

Sores caused by syphilis make
it easier to get and spread an HIV infection.

People with HIV who have a negative VDRL test should
have a second test for syphilis if the infection is suspected.

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